When MPNZ's load shedding percentage exceeds 75%, the bar on the graph should move into a red zone. It signals the USI transmission grid is approaching peak loading and as MPNZ's load shedding percentage approaches 100% there is a reasonable likelihood of new chargeable peak periods occurring.

When the end of the bar is red MPNZ is deploying its maximum load control capability (100%). The longer MPNZ load shedding remains at 100% the more likely new chargeable peak periods will occur on the USI grid. This forms a reasonable signal for consumers to manage their load and to continue doing so until the bar on graph moves down from 100% and ceases to be red at the end.

When the whole bar is white (0%) MPNZ is not controlling any load and the grid will be operating at normal load levels. This bar is updated every 5 minutes.

MainPower Trust

The MainPower Trust is the organisation which holds the shares of MainPower New Zealand Limited. The Trust has seven Trustees. Trustee elections are held every three years and Trustees are elected by the qualifying customers of MainPower.

The enactment of the Energy Companies Act 1992 required MainPower to become a company with a clear ownership structure and a Company Establishment Plan was developed for this purpose.

The MainPower Trust was established on 24 October 1995 to hold in trust the qualifying customers' and community's entitlement until such time as a distribution was made, and this is the situation right through to the present day. It was agreed MainPower's qualifying customers would be entitled to 80% of the MainPower Trust Fund including the ordinary shares that the Trust held in MainPower. The community as a whole would be entitled to the remaining 20%.

By law, the MainPower Trust must be wound up no later than 25 April 2073. The MainPower Trust assets will, unless there has been a distribution and the Trust wound up at an earlier date, vest in a charitable trust that will be known as the MainPower Foundation.